Experimental investigation and thermodynamic modeling of the Al–Cu–Si system

16 ternary alloys located over the entire composition range of the Al–Cu–Si system are investigated by means of XRD, SEM/EDX and DTA. The phase equilibria associated with the kappa phase of the Cu–Si system are determined in detail and the isothermal sections at 600 and 500 ^°C are experimentally constructed. No ternary phase is observed at 600 or 500 ^°C. A thorough thermodynamic modeling for this system is then conducted based on the critically reassessed literature data and the present experimental results.     

Precision associated with determination of dirt content of natural rubber

The precision associated with determination of dirt in natural rubber is low even when similar testing procedures are applied. All measurements leading to this estimation involve the use of an analytical balance. For this reason the contribution of associated errors to the ultimate precision of dirt measurements was evaluated using analytical balances of varying degrees of precision. A mathematical model was proposed to estimate the compound standard error associated with dirt measurements, which was found to be ±0.001 mg. This signifies that, during dirt assay, the masses of test portions, empty sieves, and sieves containing dirt must be estimated to at least 3 significant figures. This error would further decrease with an increase in the quantity of dirt assayed. Prolonged maturation of coagula reduced the length of rubber chains, thus increasing the ease of dissolution of test portions during dirt analysis. Higher molar mass samples were mostly associated with poor reproducibility of dirt and macrogel content determinations. Increasing the mass of test portions improved the precision of dirt measurements, though the recommended sizes of these portions should be a compromise of economic considerations and practical testing conditions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 957–962, 2001     

Bunsen section thermodynamic model for hydrogen production by the sulfur–iodine cycle

A model for the Bunsen section of the Sulfur–Iodine thermo-chemical cycle is proposed, where sulfur dioxide reacts with excess water and iodine to produce two demixing liquid aqueous phases (H₂SO₄ rich and HI rich) in equilibrium. Considering the mild temperature and pressure conditions, the UNIQUAC activity coefficient model combined with Engels' solvation model is used. The complete model is discussed, with HI solvation by water and by iodine as well as H₂SO₄ solvation by water, leading to a very high complexity with almost hundred parameters to be estimated from experimental data. Taking into account the water excess, a successful reduced model with only 15 parameters is proposed after defining new apparent species. Acids total dissociation and total H⁺ solvation by water are the main assumptions. Results show a good agreement with published experimental data between 25 °C and 120 °C.     

Phase and microstructure of tungsten coating on C/C composite prepared by double-glow plasma

W-coated C/C composite is the most interesting as the ITER plasma facing components. In this paper, a dense W-modified layer was prepared on the C/C composite substrate by double-glow plasma method using pure W as target. Argon was input into the chamber as the plasma and the reactive gas. Phase and microstructure of as-prepared coating were examined by the X-ray diffraction and scanning electron microscopy, respectively. The results indicated that the dense W-modified layer could be successfully coated on the surface of the C/C composite substrate by double-glow plasma method. The W-modified layer was made of many columnar grains extending perpendicularly outward from the C/C composite substrate. There was a transition layer honeycomb-like between W coating and the C/C composite substrate. The adhesive force of the W coating and C/C substrate was about 21 N.     

The PZT system (PbTixZr1−xO3, 0≤x≤1.0): High temperature X-ray diffraction studies. Complete x-T phase diagram of real solid solutions (Part 3)

Based on high temperature x-ray diffraction studies of the PZT system (PbTi_xZr_1−xO₃, 0.0≤x≤1.0) the complete x-T phase diagram of solid solutions is built, which exhibits peculiar properties due to the real structure of ceramics:     

Structural Transformation and Pressure-Induced Phase Transition in PZT

Angle-dispersive X-ray diffraction and Raman scattering measurements were carried out to follow the crystal-to-crystal transformation occurring in PbZr 0.52 Ti 0.48 O 3 ceramic powders with either increasing hydrostatic pressure or decreasing temperature. A low-temperature monoclinic phase was confirmed to exist below 298 K. External pressures of several GPa were found to fundamentally alter the structural and polar properties of PZT near the MPB and novel phase transitions were found to occur at close to 5GPa at 298 K, 7.5 GPa at 154 K and 9 GPa at 44 K. Whereas X-ray diffraction data indicated no deviation from the cubic symmetry above these pressures at each given temperatures, the unusually strong and persistent Raman signals, similar to relaxor-specific spectral signatures, indicated the presence of symmetry-breaking disorder in this phase. Based on these results, an updated version of the Pressure-Temperature phase diagram is proposed.     

次烟煤对冲燃烧锅炉对煤粉细度和运行氧量的适应性研究

国电康平发电有限公司2号发电机组锅炉自投产以来,灰渣可燃物含量很低,希望通过对运行氧量及煤粉细度等方面的调整,控制灰渣可燃物含量,减少制粉系统电耗及磨损,降低排烟损失,使机组经济性提高.文中介绍了煤粉细度和氧量调整对灰渣可燃物含量及锅炉效率等方面的影响,通过试验分析该锅炉对煤粉细度及运行氧量变化的适应性.     

Phase change memory alloys: GST cell array characterization using picosecond ultrasonics

Phase change random access memory alloys (PRAM or PCM) are a class of non-volatile memory that is thought as viable alternatives to flash memory technology or to supplement other memory technologies depending on the end applications and its key performance requirements. Ge₂Sb₂Te₅ alloy (GST) is the most widely used chalcogenide material for PCM application, and has many unique properties, including strong temperature-dependent film properties, low thermal conductivity, and high electrical resistivity. Picosecond ultrasonics was used to make non-contact, non-destructive measurements of GST films on blanket wafers and directly on product wafers. On-product wafer measurements were made on various via array (0.5 μm and 1 μm between cell edges with CD size from 250 to 800 nm). Measurements have shown excellent correlation to cross-section SEM and were consistent with CMP polish times for both blanket and pattern wafer measurement. Excellent repeatability based on extensive measurements demonstrates the capability and reliability of picosecond ultrasonic technology. Picosecond ultrasonic measurements also provide rapid characterization across the whole wafer at production-worthy throughputs.     

Essential and trace elements content of commercial infant foods in the UK

There is a paucity of data in respect of the nutritional quality of complementary foods for infants and young children aged between 6 and 12 months. The primary objective of this study was to examine nutritive values of such complementary infant food on the UK market in order to ascertain their suitability relative to dietary guidelines for the 6–9 months age group. Quantitative analyses were conducted on eight different products representing four popular brands (meat and vegetable based) currently on sale in the UK. Eight major mineral and trace elements, namely: calcium, copper, magnesium, iron, zinc, potassium, sodium and selenium were measured by ICP–OES and ICP–MS. The results of these studies were referenced to the Recommended Nutrient Intake (RNI) values for 6–9 months old children, and a menu of entire daily intake of minerals and trace elements was composed taking into consideration the nutrient and energy intake from milk consumption. Based on these comparisons, all the food samples studied in this work contained less essential minerals than expected from the RNI values except for potassium in meat and vegetable based recipes. These results suggest that commercial complementary infant foods on the UK market may not contain the minimum levels of minerals required for the labelling declaration of micronutrient content (Commission Directive 2006/125/EC). This provides opportunities and scope for product optimisation to improve their nutritive value.